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Bruised Toenail From Running? What To Do About Runner’s Toe

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As a competitive distance runner and certified running coach, I’ve always been thankful that my uncle is a podiatrist.

Between plantar fasciitis, blisters, extensor tendonitis on the top of the foot, and bunions, distance runners are prone to a myriad of foot problems, so I’ve certainly taken advantage of his 50+ years as a podiatrist to answer various foot care issues over the years.

A black toenail or a bruised toenail from running is another common foot problem for long-distance runners. 

Black toenails in runners are usually due to accumulated microtraumas from the toenails repeatedly bumping into the end of the shoe, but there can be other causes.

In this guide, we will discuss risk factors and causes of a bruised toenail from running, how to prevent them, and treatment options for black toenails after running.

A person looking at their toenail.

Why Do I Have A Bruised Toenail From Running?

A black or bruised toenail from running is called a subungual hematoma.1Tully, A. S., Trayes, K. P., & Studdiford, J. S. (2012). Evaluation of Nail Abnormalities. American Family Physician85(8), 779–787. https://www.aafp.org/pubs/afp/issues/2012/0415/p779.html

‌“Subungual” means under the toenail, and a “hematoma” is a bruise.

Bruising anywhere on the body is essentially blood trapped under the skin, so the reason your toenail looks black, purple, dark red, or discolored is a buildup of pooled blood under the toenail that has leaked out from broken blood vessels that feed the nail bed.

Black toenails from running are so common that this condition is often referred to as runner’s toe (or runner’s toenail or jogger’s toe).

If the damage to the blood vessels under the nail bed is significant, nutrients won’t be able to perfuse the nail bed, and the toenail will eventually die and then fall off.

Eventually, a new nail will grow, but this can take 6-9 months.

Bruised toenail with a sad face drawn on it with a marker.

What Causes Black Toenails After Running?

Rather than resulting from one acute misstep while on the run, a running toenail bruise typically occur due to accumulated microtraumas.

These are, namely, from when the nail of the big toe, second toe, or other toes repeatedly slam against the inside front of your shoe or experiences constant pressure from the toe box on the top of the shoe pressing down.

Blood trapped under the toenail can also be due to a blood blister. 

Blood blisters under the toenail usually result from repetitive trauma of the top of the toe box compressing the toenail and toe when you push off or repetitive friction over damp or sensitive skin.

There are also other potential causes of discoloration of toenails in runners, including the following:

Speak with your healthcare provider If you have concerns about the above conditions.

A person running.

What Are the Symptoms of Runner’s Toe?

If the toenail on your big toe, second toe, or longest toe is black or blue from running, you likely have runner’s toe.

The big toe is the largest and often the longest or nearly the longest toe. It is the main toe used for push-off during the gait cycle. 

Therefore, the big toe is more likely to be cramped in the toe box of your running shoes, and the accumulated pressure buildup on the toenail and nail bed at push-off can injure the blood vessels supplying the nail.

The second toe is often the longest toe, so it is prone to sliding and bumping against the inside end of your running shoes if they don’t fit properly or your lacing isn’t tight enough.

Regardless of the affected toe, the black toenail may not be particularly painful, but your bruised toenail may feel tender or more sensitive if it does collide with the end of your shoe or if you press down on it. 

The most common signs and symptoms of runner’s toe include:

  • Darkening or discoloration of the toenail
  • Pain and tenderness
  • Pressure under the toenail
  • A loosening of the nail from the nail bed

Many runners with bruised toenails lose the affected toenail because the nail dies due to damage to the blood vessels supplying it. 

Runner’s toe can become infected if bacteria enters the bloodstream under the toenail, or if you lose the nail and the wound is exposed to microbes.

Signs of an infection include redness, swelling, more intense pain, warmth, and drainage or pus. 

A person with various bruised toenails.

How Do You Treat Bruised Toenails?

Runner’s toe generally isn’t a cause for concern or requires medical treatment.

As long as your black toenail isn’t hurting or impacting your running form, you should be able to keep running. 

However, it’s important that you do NOT pull the toenail off. 

To prevent an infected nail bed, soak the affected foot in warm salt water several times daily and wear clean, dry socks.

If the toenail falls off, wash the toe in warm, soapy water, coat it with an antibiotic ointment, and cover it with a sterile dressing. 

Follow this same procedure to change the dressing at least once a day, typically after a shower or anytime your sock gets dirty or moist. 

You may need to reduce your mileage by taking time off or doing low-impact cross-training until your toenail pain resolves, especially if you get an infected nail bed. 

A person running.

How Can I Prevent Back Toenails From Running?

As a Running Coach, these are the top tips I have found to be most effective at preventing black toenails from running:

  • Clip your toenails straight across rather than in a curve to prevent ingrown toenails. Trim them regularly so they are neat and do not extend beyond the end of your toe.
  • Wear running shoes that fit your foot based on the toe box’s length, width, and shape. There should be about a thumb-width distance between the end of your longest toe and the end of the running shoe. You should be able to wiggle your toes comfortably in the toe box.
  • Lace your shoes tight enough so that your foot stays in place without sliding forward. There are different lacing techniques that might prevent your foot from sliding forward.
  • If you are prone to bruised toenails, stick moleskin toe pads or silicone pads on the tips of your big toe and second toe before you run.
  • Wear moisture-wicking socks with a seamless toe and ample cushioning around the toes. The seamless toe can prevent friction blisters, and the breathable materials will prevent sweat from softening the skin and nails over the long run, which can also cause blisters. However, you don’t want your running socks to be super slippery and slick—especially if you wear orthotics or insoles that are smooth or not coated—because there won’t be enough friction so your foot slides forward and back in the shoes as you run. I like the Swiftwick Aspire 5 running socks because they are super breathable and really hug your foot. If you need more cushioning in the toenail, I love the Darn Tough Lightweight Performance Running Socks.  
  • Avoid excessive downhill running. Your toes are more likely to slam against the front of the shoe if you’re running downhill because of gravity and the angle of the slope.

If you are concerned that your blackened nail isn’t healing or you have signs of infection, seek medical care from your doctor, podiatrist, or someone who works in dermatology.

Overall, while runner’s toe isn’t as serious as most running injuries, it can still be uncomfortable and interfere with your training, especially if your toenail gets infected.

Therefore, do your best to follow the prevention strategies for runner’s toe and adjust your running shoes, lacing, and socks at the first sign of toenail pain while running to prevent further exacerbation.

For lacing patterns, see our next guide:

References

Photo of author
Amber Sayer is a Fitness, Nutrition, and Wellness Writer and Editor, as well as a NASM-Certified Nutrition Coach and UESCA-certified running, endurance nutrition, and triathlon coach. She holds two Masters Degrees—one in Exercise Science and one in Prosthetics and Orthotics. As a Certified Personal Trainer and running coach for 12 years, Amber enjoys staying active and helping others do so as well. In her free time, she likes running, cycling, cooking, and tackling any type of puzzle.

1 thought on “Bruised Toenail From Running? What To Do About Runner’s Toe”

  1. NICE!!! I finally found an answer that can help me. I have the same condition but from cycling. I saw my Dr, and he thought it was mechanical, as he could find no issues with me. I will try to tighten my shoes, add a thicker insole, and put more padding in the toe of my shoes. I hope this helps.

    Reply

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